Anyone who read our disgruntled recap of last week's Homeland will know that this episode didn't have a lot to live up to. Even if 'Tower of David' hadn't been a detailed, intriguingly downbeat episode in its own right, it would be an improvement in our book purely by virtue of not featuring any heinously out-of-character racism or a single moment of Dana.

But these parallel stories of Carrie and Brody hitting rock bottom, having both glimpsed hope and had it extinguished within a day, were genuinely compelling.

The reintroduction of Damian Lewis at this still-relatively-early stage was a welcome surprise, since it was becoming easy to picture a scenario where he was kept as a mid-season trump card. We still don't know where his travels have taken him over the past few months, but we know where the end of the line is: an unfinished Venezuelan apartment building full of squatters, junkies and perverts. And an improbably glamorous girl in Daisy Dukes, natch.

The entire subplot with Esme's crush on Brody felt pretty hokey - we know Lewis is hot, but as far as she's concerned this is a bald, possibly insane stranger who's mostly bleeding all over her floor. And yet within 24 hours she's begging to run away with him. Brody has got some moves.

But in all seriousness, Lewis was firing on all cylinders here, beautifully selling the absolute physical agony of his wounds and later the emotional anguish of his situation. He knows he will die in this place if he doesn't get out, and although his sudden mosque epiphany felt a little odd, it made sense that he'd be just desperate enough to convince himself that a safe place still existed. And in one of Homeland's most expressly bleak turns to date, his escape attempt only gets a mosque full of innocent people gunned down.

So having initially refused to take more heroin because it kept him from thinking, Brody ends the episode taking it willingly for exactly the same reason. His pleading "It's like the hole in Iraq, I can't do it again," really brought home just how horrifying this particular end of the line scenario is for him. We know Brody isn't going to die here, but the writers have literally (and doubtless intentionally) written themselves into an intriguing corner where it's hard to conceive of the way out.

And while we weren't sold on Esme, the Tower did bring with it one fascinating new addition in Erik Todd Dellums' enigmatic underground doctor. He's initially just a charismatic and entertainingly deadpan presence, and seems to have some real sympathy for Brody, but by the end of the episode we've learned he's a pedophile and in that final speech he becomes almost demonic, condemning Brody to hell. Genuinely disturbing.

As Brody accepts that he will "die here", Carrie is offered an unexpected escape route from her own cell in Virginia. Her response? "I would rather die in here." 'Tower of David' was the last episode co-written by series stalwart Henry Bromell before his death this year (he won an Emmy posthumously for last season's outstanding 'Q&A') and these small, shrewd parallels are where his stamp is felt most clearly.

We'll have to wait to discover exactly who the lawyer is working for, but the prospect of Carrie being placed in Brody's shoes – having an enemy exploit her vulnerability and try to turn her against her country - is intriguing, even if we can't see her ever seriously considering it. But the psych ward is being drawn in such a cartoonish way that that possibility feels more plausible than it should.

We complained last week about the unnecessarily cruel use of Thorazine, an older antipsychotic with severe and sometimes permanent side effects. This week, we had the weirdly played session with Carrie and her psychiatrist, who seemed to be taking a faintly sadistic pleasure in provoking her despite her obvious improvement. Being dismissive is one thing, but saying "You'll have to be a bit more cooperative than that" and openly threatening her with medication is borderline abusive.

But for now, Carrie isn't desperate enough to consider turning on the CIA, and so we're left with a very dark episode ending indeed: Carrie and Brody both in their dimly lit cells, both numbed out on their own forms of medication, both resigned to their fates.

Other thoughts:
- Our latest prediction is that Quinn, having declared himself "out" at the CIA last week, will be the one to track down Brody in Venezuela and bring him back. If anybody could pull it off, he could, and we already know he's sympathetic to Carrie. And honestly, we just need more badass Quinn in our lives, particularly after this downer of an episode.
- We promise we'll get over Breaking Bad eventually. We will. But it was impossible not to see the parallels between this ending and Breaking Bad's 'Granite State' - Carrie and Brody linked by their separate states of imprisonment much like Walt and Jesse in that penultimate episode.
- "Must be some favour," the doctor says regarding El Nino's loyalty to Carrie, and he's right. What kind of history could Carrie have with this apparent lowlife?
- Bankers are really getting it in the neck on Homeland this season, between last week's evil HLBC suits and this week's egomaniacal David, in whose unfinished tower Brody has been left to rot.
- Was the law firm paying off Carrie's nurse, or was she just genuinely sympathetic to her plight? Your answers below…